We have previously described the isolation and partial characterization of Alt-1, a major glycoprotein allergen from Alternaria tenuis. In the proposed studies we will further define the physicochemical characteristics of Alt-1 and determine whether allergenic determinants are present on the carbohydrate or protein portion of the molecule. We postulate that Alt-1 is present on airborne particles smaller than intact Alternaria spores and that these particles are respirable into the tracheobronchial tree. We will measure by immunochemical means the atmospheric Alt-1 content over a four-month period; in addition, the immunologic response to Alt-1 will be measured in both non-allergic and mild-sensitive patients. We will also carry out a placebo-controlled mold immunotherapy program, using both Alt-1 and a crude Alternaria extract of measured Alt-1 content as immunizing agents. The clinical efficacy of this treatment will be tested by quantitative nasal and/or bronchial inhalation challenges before and after therapy. Finally, we will establish lymphocyte cultures from mold-sensitive patients to measure the in-vitro production of Alt-1 IgE antibody; this will enable us to test the ability of chemically modified Alt-1 preparations to diminish or abolish Alt-1 IgE antibody production.